Add ETL Contract Checks (#619)

* Adds dev dependencies to requirements.txt and re-runs black on codebase

* Adds test and code for national risk index etl, still in progress

* Removes test_data from .gitignore

* Adds test data to nation_risk_index tests

* Creates tests and ETL class for NRI data

* Adds tests for load() and transform() methods of NationalRiskIndexETL

* Updates README.md with info about the NRI dataset

* Adds to dos

* Moves tests and test data into a tests/ dir in national_risk_index

* Moves tmp_dir for tests into data/tmp/tests/

* Promotes fixtures to conftest and relocates national_risk_index tests:
The relocation of national_risk_index tests is necessary because tests 
can only use fixtures specified in conftests within the same package

* Fixes issue with df.equals() in test_transform()

* Files reformatted by black

* Commit changes to other files after re-running black

* Fixes unused import that caused lint checks to fail

* Moves tests/ directory to app root for data_pipeline

* Adds new methods to ExtractTransformLoad base class:
- __init__() Initializes class attributes
- _get_census_fips_codes() Loads a dataframe with the fips codes for 
census block group and tract
- validate_init() Checks that the class was initialized correctly
- validate_output() Checks that the output was loaded correctly

* Adds test for ExtractTransformLoad.__init__() and base.py

* Fixes failing flake8 test

* Changes geo_col to geoid_col and changes is_dataset to is_census in yaml

* Adds test for validate_output()

* Adds remaining tests

* Removes is_dataset from init method

* Makes CENSUS_CSV a class attribute instead of a class global:
This ensures that CENSUS_CSV is only set when the ETL class is for a 
non-census dataset and removes the need to overwrite the value in 
mock_etl fixture

* Re-formats files with black and fixes broken tox tests

data/data-pipeline/data_pipeline/application.py

@@ -3,7 +3,12 @@ import sys
 import click
 
 from data_pipeline.config import settings
-from data_pipeline.etl.runner import etl_runner, score_generate, score_geo, score_post
+from data_pipeline.etl.runner import (
+    etl_runner,
+    score_generate,
+    score_geo,
+    score_post,
+)
 from data_pipeline.etl.sources.census.etl_utils import (
     reset_data_directories as census_reset,
 )